Thank you very much for your replies although I am a bit dispirited that the consensus seems to be that DD and SIL are solely out for financial gain. I do believe that is probably true of SIL, but I also believe that DD loves me and genuinely wants a reconciliation. However, I am very mindful of the risks and extremely afraid of being hurt again through DGC. I get the impression that they regard any access to DGC as a privilege which will only be afforded to me if I am compliant.
For those of you who have asked about the background, there were several threads, several years ago, the first one nearly four years ago. I am sorry if this is making my post long but, briefly, the background is that DD met SIL in her shared house in her second year at university, he was 3rd year. They wanted to buy a house together in the university town, where prices were still relatively affordable. He asked his grandparents for some money which they had apparently been saving for him, and DD asked if I would do the same. At the time my feelings were that it would give her a good start in life and so I agreed. He was doing an engineering degree and she already had a professional cookery qualification as well as doing a degree, so I thought that they would be set fair. I also intended to help her two younger sisters in due course.
SIL, or BF as he was then, seemed alright - quiet and a bit socially awkward, he never seemed to make much of an effort to get to know us - but nothing to be concerned about, and DD was very happy. However, given that they were still young and not married, I said to DD that although I would help her, the money would be expressed as a loan, to be protected by a Deed of Trust. SIL was not happy at this, as he wanted to own it jointly and I began to see a different side to him.
I was concerned about DD and started a thread on which the consensus was that there were a lot of red flags. ( 'Lobster Boy' was a phrase coined by a poster referring to how SIL ordered lobster when I took him and DD out for lunch, but is not significant in the overall scheme of things). There were aspects of SIL's behaviour which seemed controlling, such as he tried to stop her from going with her friends on a holiday which she had booked before she met him, was telling her fellow tenants what to do in a student house in which he was not a tenant (she was 3rd year by then and he was doing a year in industry as part of what was intended to be a 5 year Masters), and insisted on her driving over a 100 miles to apologise to him after some row. Also, DD now seemed to be very unhappy, crying all of the time, constant rows, it wasn't what it had been.
In addition, they didn't seem to have any plans for the future other than buying the house and doing it up for a profit. SIL walked out of his year in industry as he felt that they weren't giving him big enough projects, destroying his files on the way out and sending a rude message to his employers. I subsequently withdrew from the proposed purchase after the incident described above, where DD had locked herself in the bathroom sobbing and he wouldn't leave. I do not believe that he has ever forgiven me for that.
Anyway, turning to the present, DD is reconciled with me and DH although I am the only one she communicates with on a regular basis. She and DD3 exchanged birthday texts but DD3 is very hurt by her behaviour and DD2 has had no contact with her for over three years, after SIL sent an email to the family after DD2's graduation in which he criticised her and accused all of us of not welcoming him and treating him like a son (He also said I should 'make amends' about the house). DD2 didn't really care what SIL thought, but she was so hurt that the email had been sent with DD1's approval. The estrangement has put strain on other family relationships and I know that I have probably leant on DD2 and DD3 more than I should have done but, overall, I would say that we are all much closer. DD2 and DD3 now have a very close relationship, which is lovely and I see a lot of both of them. I know that it is essential not to lose sight of those who remain in your life and who love you and who are there for you, and I think sometimes DD2 and DD3 feel that I have been too accommodating to DD1 and allowed her to take over my headspace too much. They are also protective of me. They are open to having a relationship with DD1 and their nieces in the future, but not now.
As onemoresurvey says, I can't pass up the opportunity for reconciliation. I have to take that risk because she is my daughter and I love her. Also she and DGDs may need me in the future. I do want to meet is parents as I hope it may help me to understand things better. Apparently they told SIL and DD that they should tell us about DGD1. They sound nice and supportive but goodness knows what they have been told about us.
The bursary is about £26k tax free, I think, as they both did subjects which attract the higher amount so, combined with all of the government loans, it is not bad. That is why they wanted to 'borrow' the money from us, to buy another property to let out but without a mortgage. I suspect that is partly why DD1 is doing the PGCE, with the intention of buying another property to do up and let out. However, it will require her relocation to the other end of the country. We had agreed to help by paying rent etc on the property, but DD1 is now mentioning that they will need childcare as it would be too much for SIL to look after the DGDs on his own. I am worried as to what exactly they are expecting, to be honest. I suspect that if SIL is not satisfied, he will be telling DD1 that her awful family have let them down, yet again. There will have to be a conversation but obviously not now and I will probably let DH deal with it, as he is better at these things - calmer and more matter of fact.
I also share interestedwoman's concerns as to whether or not DD1 will cope with the course, especially with no support nearby. I get the impression that she does virtually all of the shopping, cooking and childcare at present. She recently had to cancel an appointment with her consultant when DGD1 was poorly even though SIL is not working. She has also been carrying out painting and decorating to the new house even in the last week, when she is so close to giving birth. From what I have seen DD1 is an excellent mother and DGD1 is clearly very much loved and cared for.
Gosh, that was long, sorry, but it is helping me to gain a bit of perspective by writing it down.